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Signs of Food Allergies Might Be in Newborns’ Blood

Overactive immune cells could prime the immune system to attack normally harmless molecules found in food

Testing for allergies (Astier/BSIP/Corbis)
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Food allergies can be terrifying and even life threatening if the wrong food sneaks into a meal. But the threat could be lessened if there was a reliable test to identify allergy-prone kids before they ever even encounter cow's milk, eggs, peanuts or other common food allergens. Mitch Leslie reports for Science that this hope could become a reality with a new study that suggests that the signatures of an over-active immune system can be found in newborns' blood.

Researchers led by Yuxia Zhang, an immunologist at the Walter and Eliza Hall Institute of Medical Research in Australia studied more than 1,000 newborns. They took blood from the children's umbilical cords and profiled the immune cells and molecules floating within, the team writes in the paper published in Science Translational Medicine. The children were then tested for food allergies a year later. 

Based on these tests, the team was able to pinpoint a type of immune cell called a monocyte, whose numbers were higher in the cord blood of kids who went on to develop food allergies. Monocytes transform into pathogen-fighting cells when they encounter an invader. In lab tests, the monocytes of children who developed allergies transformed more readily (were more eager to fight) than the monocytes from kids without allergies.

"Normally, a strong response is good; it means the immune cells are ready to fight bacteria and viruses," writes Tina Hesman Saey for Science News. But in food-allergic kids, the researchers suspect that such over-active monocytes could keep the immune system in a state of high alert, signaling another kind of immune cell, called a T cell, to transform and stoke the immune system to react. As a result, these eager-to-fight monocytes provoke a cascade of different molecules and cells to react to normally harmless things like a peanut protein. 

Even so, the result wasn't ironclad. "There are some babies with the signature that don't develop food allergies, which suggests other factors come into play in the first year of life," says Lee Harrison, an immunologist on the research team, reports Bridie Smith for The Sydney Morning Herald.

Immune systems are so complex, and the variety of factors that influence pregnancy and a child's development so intertwined, that although the results of this study are promising, they likely offer only part of the overall picture. Genes, the mother's diet, the baby's exposure to food and other factors might play into the development of allergies. 

Understanding all those factors will be necessary in finding any way to prevent food allergies. But for now the finding offers an intriguing new way to look at how allergies might develop. 

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